The present invention relates generally to the art of promoting plant growth, and more particularly, is concerned with apparatus which aids in the promotion of plant growth through the use of artificial light.
It is well known that artificial light promotes plant growth. It is also well-known that certain light wavelengths are particularly effective in the promotion of plant growth. As a result, a significant effort has been made by the industry, in light of the current interest in using plants in environments which often lack natural light, such as homes an offices, to develop special-purpose lamps, generally referred to as plant lamps. Many of the major lamp manufacturers have designed, and are currently marketing, lamps which are advertised to be of particular efficacy in the promotion of plant growth. These plant lamps produce most of their light in certain spectral energy bands, i.e., at those wavelengths which have been found to promote plant growth. These plant lamps usually contain special phosphors to produce those light wavelengths which are known to stimulate plant growth. Substantial success with such plant lamps has been demonstrated in a wide variety of circumstances.
As a consequence of both the research findings and the results obtained by the use of such plant lamps, the research efforts of industry in this field have been directed uniformly to the design and development of special purpose lamps.
However, such special-purpose, i.e., plant, lamps have the disadvantage of being significantly more expensive than their counterpart fluorescent or incandescent lamps. Additionally, the plant lamps, being directed as they are to a very specialized market, are offered in a limited number of sizes, configurations, and power ratings, as compared with their counterpart conventional lamps.
Furthermore, when the plant lamps are used with the available lamp fixtures, only 17-20% of the total light energy emitted by the plant lamp is actually delivered to the plants. The remainder is directed elsewhere and hence does not contribute to promoting plant growth. Such a low use efficiency, however, has not heretofore been considered important by the industry, however, because the wavelength, rather than the amount, of light delivered to the plants was considered the overriding consideration in promoting plant growth.
Additionally, the combination of plant lamps with the available light fixtures result in uneven plant growth patterns, thus reducing the effectiveness of the combination, due to a lack of uniformity in the light level delivered to the plants in a direction transverse of the light source.
Apart from the above disadvantages, it has been demonstrated in addition that plant lamps per se as such do not have quite the originally suspected advantage over their counterpart conventional lamps in promoting plant growth. Contrary, conventional lamps, i.e., fluorescent, have also been found to produce good results in promoting plant growth. These results, however, have been largely ignored by the industry and the direction of research effort has heretofore been channeled nearly exclusively in developing increasingly sophisticated, and hence more expensive, plant lamps.
In view of the above, it is a general object of the present invention to provide a plant lighting fixture which, when used in combination with a source of artificial light, overcomes one or more of the disadvantages of the prior art specified above.
It is another object of the present invention to provide such a plant lighting fixture which may be used in combination with both plant lamps and conventional lamps.
It is a further object of the present invention to provide such a plant lighting fixture which substantially increases the amount of light delivered to the plants.
It is an additional object of the present invention to provide such a plant lighting fixture which substantially increases the capability of conventional lamps to promote plant growth.
It is yet another object of the present invention to provide such a plant lighting fixture which reduces the amount of glare light.
It is a still further object of the present invention to provide such a plant lighting fixture which delivers uniform light energy over a defined surface area.